WPMU DEV Avatars Plugin
Avatars you control for both sites and users on your WordPress Multisite network.
Avatars lets Multisite users upload, manage, and share profile and site avatars.
From ‘selfies’ to company logos, images help us personally connect with other users and companies on the web.
WPMU DEV Avatars Plugin plugin integrates profile images in a way that feels native to WordPress core. Adding a simple avatars settings feature to the user profile, and a ‘Site Avatar’ option under ‘Settings’, brings a surprising new level of user participation.
Please visit official plugin page for more information